As electronic devices continue to become more feature rich, the extra functionality typically requires the addition of circuitry to the electronic devices. The additional circuitry being added to the electronic devices usually takes the form of integrated circuits, be it in the form of extra integrated circuits or revisions of existing integrated circuits with more functional parts. While integrated circuits typically offer enhanced reliability and lower power consumption over discrete components, the addition of extra integrated circuits usually means that the electronic devices will incur an increase in power consumption. Increased power consumption may be undesirable, especially for wireless electronic devices, wherein the increased power consumption may shorten the operating time between charges of a battery providing power to a wireless electronic device.
In an electronic device with a wide array of features, it may be atypical for more than a few of the features to be in use at any given time. For example, in a smart communications device containing a cellular telephone, a web browser, a personal digital assistant, a pager, a multimedia player, a navigation device, and so forth, the use of a single feature often precludes the use of many of the remaining features. For example, when a user is speaking on the cellular telephone, it is unlikely that the multimedia player will also be in active use. Therefore, power may be eliminated from integrated circuitry implementing the features not in use to help reduce power consumption.
A prior art technique commonly used to help reduce power consumption involves the partitioning of an integrated circuit(s) into power domains. When a circuit in a power domain is needed, then all circuitry in the power domain is powered. If no circuitry in a power domain is needed, then none of the circuitry in the power domain is powered. Enhancements to the technique have added hierarchical power domain trees to increase control over which circuits to turn on and which to turn off, while other enhancements have helped to resolve signal routing problems and power rail stability.
However, a disadvantage of prior art techniques is that they often ignore circuitry that may perform many different functions, which may make it difficult to determine which portions of the circuit to turn on or turn off. Therefore, a significant portion of circuitry in an electronic device may not have power consumption control.
Another disadvantage of prior art techniques is that they may negatively impact the performance of the circuitry in the electronic device. Software is commonly used to control the state of the various power domains. Since software may be slow in shutting down or powering up a power domain, the state of circuitry within a power domain may need to be known prior to when the circuitry actually needs to be shut down or powered up.
Yet another disadvantage of prior art techniques is that the power control hardware and software is typically added by designers of the electronic device, which may significantly complicate the design and development process.